This application claims priority from provisional application Ser. No. 61/808,783 filed Apr. 5, 2013, which is incorporated herein by reference in its entirety.
This invention was made with government support under Grant No. U.S. Pat. No. 1,117,178 awarded by the National Science Foundation. The government has certain rights in the invention.
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OF THE INVENTION
The invention is related to the field of modular robots, and in particular to modular angular-momentum driven magnetically connected robots.
The prior art includes self-reconfiguring lattice-based modular robots that can be broadly categorized by two attributes: the mode of locomotion and the connection mechanism. Perhaps the most elegant model for locomotion is termed the sliding cube model. In this model, cubes translate (i.e. slide) from one lattice position to another. Despite its theoretical simplicity, no hardware implements this approach in the general 3D case. There are two systems, which implement a 2D version of the sliding cube model in the vertical plane and two systems that operate horizontally. Not only are all of these systems mechanically complex, it is not clear how any of these systems could be extended to 3D.
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OF THE INVENTION
According to one aspect of the invention, there is provided a self-configuring robot. The modular robot includes a frame structure that includes a plurality of cylindrical bonding magnets positioned along the edges of the frame structure, the frame structure includes magnetic, non-gendered, hinges on any of the edges of the frame, the hinges provide enough force to maintain a pivot axis through various motions, the cylindrical bonding magnets are free to rotate. A movement generator is positioned within the frame structure that applies a torque about the pivot axis to generate multi-axis movement allowing independent locomotion.
According to another aspect of the invention, there is provided there is provided a self-configuring robot. The self-configuring robot includes a frame structure having a plurality of cylindrical bonding magnets positioned along the edges of the frame structure. The frame structure includes magnetic, non-gendered, hinges on any of the edges of the frame. The hinges provide enough force to maintain a pivot axis through various motions. The cylindrical bonding magnets are free to rotate allowing for multiple self-configurations with another modular structure having magnetic properties. An actuator is positioned within the frame structure that includes a belt and a flywheel structure where the actuator is used to tighten the belt that rapidly decelerates the flywheel to create an impulse of torque generating multi-axis movement allowing both robust self-reconfiguration with the other modular structure and independent locomotion.
According to another aspect of the invention, there is provided a modular robotic system. The modular robotic system includes a plurality of self-configuring robots. Each self-configuring robot includes a frame structure having a plurality of cylindrical bonding magnets positioned along the edges of the frame structure. The frame structure includes magnetic, non-gendered, hinges on any of the edges of the frame. The hinges provide enough force to maintain a pivot axis through various motions. The cylindrical bonding magnets are free to rotate allowing for multiple self-configurations with other like self-configuring robots. A movement generator is positioned within the frame structure that pivots to generate multi-axis movement allowing both robust self-reconfiguration with the other self-configuring robots and independent locomotion.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1A-1C are schematic diagrams illustrating the various embodiments of the inventive M-Block system used in accordance with the invention;
FIG. 2 is a schematic diagram illustrating the cubic frame used by the M-Block system;
FIG. 3 is a schematic diagram illustrating the magnetic bonding used in accordance with the invention;
FIGS. 4A-4B are schematic diagrams illustrating the details of the actuator system used in accordance with the invention;
FIGS. 5A-5C are schematic diagrams illustrating the motions performed by an M-Block module;
FIG. 6 is a schematic diagram illustrating the details of calculating the physical interactions of an M-Block module;
FIGS. 7A-7E are schematic diagrams illustrating selective lattice configurations formed in accordance with the invention;
FIG. 8 is a table illustrating experimental results for controlled tests of various motion primitives;
FIGS. 9A-9C are schematic diagrams illustrating groups of M-Block modules moving as rigid assemblies;
FIG. 10 is a graph illustrating the angular velocity profile of the inertial actuator\'s flywheel as measured by an optical encoder; and
FIG. 11A-11C are graphs illustrating the pull strength of various conditions of the magnetic hinges as measured with a custom-built testing fixture.
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OF THE INVENTION
The inventions involves a novel self-assembling, self-reconfiguring cubic robot that uses pivoting actuation to change its intended geometry. Each individual module can pivot to move linearly on a substrate of stationary modules. The modules can use the same operation to perform convex and concave transitions to change planes. Each module can also move independently to traverse planar unstructured environments. The modules achieve these movements by quickly transferring angular moment accumulated in a flywheel to the body of the cube. The system provides a simplified realization of the modular actions required by the sliding cube model using pivoting.
The invention is most closely related to existing systems whose modules pivot about the edges they share with their neighbors. These existing pivoting systems are confined to the horizontal plane and use complex connection mechanisms and/or external actuation mechanisms to achieve reconfiguration. These prior works make no attempt to define a generalized, three-dimensional model for reconfiguration through pivoting. The invention presents a physical pivoting cube model that can be applied to both solitary modules and groups acting in synchrony by capturing physical quantities including mass, inertia, and bonding forces.
The other defining characteristic of any modular robotic system is its connectors. Many modular systems use mechanical latches to connect neighboring modules. Mechanical latches typically suffer from mechanical complexity and an inability to handle misalignment. Other systems such as the Catoms, Molecule, and E-MCube use electromagnets for inter-module connections. Electromagnets consume more power and are not as strong as mechanical latches. Electro-permanent magnets are an attractive alternative because they only consume power when changing state, but they still require high instantaneous currents to actuate and are not readily available. One unique system uses fluid forces to join neighboring modules, but must operate while submerged in viscous fluid. Another, the Catoms uses electrostatic forces for bonding. The unifying feature of all of these connection mechanisms is that their holding force can be controlled: on, off, or somewhere in-between. This adds complexity and decreases robustness.
In contrast to all of the systems of the prior art, the invention uses a simple mode of location (pivoting), a simple inertial actuator (a flywheel and brake), and a simple bonding mechanism (permanent magnets). Actuation through inertial control has been used extensively in space and underwater robotics as well as several earth-bound applications. There are certain systems in the prior art that uses the inertia of the modules to induce pivoting, but the necessary forces are applied externally; the system is only two-dimensional; and the modules are constrained to 180 degree rotations. The simplicity of the M-Blocks, with their self-contained inertial actuators, allows the invention to achieve both robust self-reconfiguration and independent locomotion in 3D environments.
As shown in FIG. 1, an M-Block 12 is constructed from a 50 mm cubic frame 4 milled from a single piece of 7075 aluminum and the module has a moment of inertial of 63×10−6 kg m2. However, other firm materials, such as plastic or the like can be used as well. This frame 4 holds twenty-four cylindrical bonding magnets 5 along its twelve edges. Bolt-on panels 6 are attached to the six faces. These panels 6 contain various electrical and mechanical elements such as the inertial actuator 3 and the control PCB 8. Additionally, each of these panels 6 is inset with eight outward-facing magnets 7 that assist in alignment between neighbors.